In a news brief, the Office of the Inspector General National Police Service said gunmen entered the Kenyan university's gate at around 5:30 a.m. and "shot indiscriminately" while inside the campus. The statement said a shootout began between the gunmen and campus police, causing the attackers to retreat and enter the student dorms.

I urge Kenyans to remain calm as our officers work to make sure that the attackers are ejected from the hostel and normalcy returns within the shortest time possible.

A policewoman told Reuters that two guards manning the university gate were killed. She also said that the gunmen likely took student hostages since many are trapped within the Garissa campus.

We can hear gunshots from inside the compound but at this point we can't tell who is shooting at who or what.

According to some of the students who escaped, there are around five gunmen and they entered the university dormitory while students were sleeping. ... It is hard to tell (about casualties) because the area is now cordoned off, and it is heavily guarded. At the moment, I can hear sirens, and at some point I could hear an exchange of gunfire.

No group has claimed responsibility as of late Thursday morning. But Al Shabab militants from Somalia have previously targeted Kenya. The extremist group claimed responsibility for the 2013 attack at a Westgate shopping mall in Nairobi, where 67 people were killed. Both the United States and the UK consider Al Shabab a terrorist group.